Carotid angioplasty is a rapidly evolving endovascular treatment for carotid stenosis, and advocates predict that is will replace surgical endarterectomy. The hemodynamic changes following angioplasty (whether the flow remains simple or laminar, or becomes a three-dimensional complicated flow with a non-trivial spectrum of frequencies and regions of recirculation) are not well described. Flow characteristics may prove to be predictive of disease outcome and treatment efficacy after carotid endarterectomy or angioplasty. Therefore, we propose that characterizing flow according to its laminar or complicated properties will provide a more effective means to predict arterial changes seen at the histological level and differences in restenosis and stroke risk. MRI provides a non-invasive and radiation-free method of obtaining accurate arterial information, making it an ideal modality to study arterial flow in both an experimental and clinical setting. Ultimately this technique can be investigated in a clinical setting to study flow characteristics in the human carotid artery before and after angioplasty or endarterectomy, and used to predict treatment outcome on an individual patient basis. [unreadable] [unreadable] [unreadable]